Modeling healthcare costs in simultaneous presence of asymmetry,heteroscedasticity and correlation

Highly skewed outcome distributions observed across clusters are common in medical research. The aim of this paper is to understand how regression models widely used for accommodating asymmetry fit clustered data under heteroscedasticity. In a simulation study, we provide evidence on the performance of the Gamma Generalized Linear Mixed Model (GLMM) and log-Linear Mixed-Effect (LME) model under a variety of data-generating mechanisms. Two case studies from health expenditures literature, the cost of strategies after myocardial infarction randomized clinical trial on the cost of strategies after myocardial infarction and the European Pressure Ulcer Advisory Panel hospital prevalence survey of pressure ulcers, are analyzed and discussed. According to simulation results, the log-LME model for a Gamma response can lead to estimations that are biased by as much as 10% of the true value, depending on the error variance. In the Gamma GLMM, the bias never exceeds 1%, regardless of the extent of heteroscedasticity, and the confidence intervals perform as nominally stated under most conditions. The Gamma GLMM with a log link seems to be more robust to both Gamma and log-normal generating mechanisms than the log-LME model.     

Telephone survey respondents' reactions to questions regarding interpersonal violence

Concerns have been raised regarding the appropriateness of asking about violence victimization in telephone interviews and whether asking such questions increases respondents' distress or risk for harm. However, no large-scale studies have evaluated the impact of asking such questions during a telephone interview. This study explored respondents' reactions to questions regarding violence in two large recently completed telephone surveys. After respondents were asked about violence, they were asked if they thought surveys should ask such questions and whether they felt upset or afraid because of the questions. In both surveys, the majority of respondents (regardless of their victimization history) were willing to answer questions about violence and were not upset or afraid because of the questions. More than 92% of respondents thought such questions should be asked. These results challenge commonly held beliefs and assumptions and provide some assurance to those concerned with the ethical collection of data on violent victimization.     

Bayesian sample size determination for phase IIA clinical trials using historical data and semi‐parametric prior's elicitation

The Simon's two‐stage design is the most commonly applied among multi‐stage designs in phase IIA clinical trials. It combines the sample sizes at the two stages in order to minimize either the expected or the maximum sample size. When the uncertainty about pre‐trial beliefs on the expected or desired response rate is high, a Bayesian alternative should be considered since it allows to deal with the entire distribution of the parameter of interest in a more natural way. In this setting, a crucial issue is how to construct a distribution from the available summaries to use as a clinical prior in a Bayesian design. In this work, we explore the Bayesian counterparts of the Simon's two‐stage design based on the predictive version of the single threshold design. This design requires specifying two prior distributions: the analysis prior, which is used to compute the posterior probabilities, and the design prior, which is employed to obtain the prior predictive distribution. While the usual approach is to build beta priors for carrying out a conjugate analysis, we derived both the analysis and the design distributions through linear combinations of B‐splines. The motivating example is the planning of the phase IIA two‐stage trial on anti‐HER2 DNA vaccine in breast cancer, where initial beliefs formed from elicited experts' opinions and historical data showed a high level of uncertainty. In a sample size determination problem, the impact of different priors is evaluated.     

Efficient computation of location depth contours by methods of computational geometry

The concept of location depth was introduced as a way to extend the univariate notion of ranking to a bivariate configuration of data points. It has been used successfully for robust estimation, hypothesis testing, and graphical display. The depth contours form a collection of nested polygons, and the center of the deepest contour is called the Tukey median. The only available implemented algorithms for the depth contours and the Tukey median are slow, which limits their usefulness. In this paper we describe an optimal algorithm which computes all bivariate depth contours in O(n ²) time and space, using topological sweep of the dual arrangement of lines. Once these contours are known, the location depth of any point can be computed in O(log² n) time with no additional preprocessing or in O(log n) time after O(n ²) preprocessing. We provide fast implementations of these algorithms to allow their use in everyday statistical practice.     

Product Design: a Review and Research Agenda for Management Studies

This paper reviews research on product design in the broad domain of business studies. It highlights established and emerging perspectives and lines of inquiry, and organizes them around three core areas, corresponding to different stages of the design process (design activities, design choices, design results). Avenues for further research at the intersection of these bodies of research are identified and discussed, and the authors argue that management scholars possess conceptual and methodological tools suited to enriching research on design and effectively pursuing lines of investigation only partially addressed by other communities, such as the construction and deployment of design capabilities, or the organizational and institutional context of design activities.     

Gender symmetry in dating intimate partner violence: does similar behavior imply similar constructs?

The present study examined the extent to which there is gender symmetry in the topography and experience of dating intimate partner violence (IPV). Self-report data were collected from 450 undergraduate men and women at a large Southeastern university. Perpetration and victimization rates were examined, as were context, function, and experience of fear. Results support the view that dating IPV is generally symmetrical at a topographical level, although significantly more women than men reported perpetration of severe physical assault. However, gender asymmetries were found in the context, function, and experience of fear. These findings suggest that gender-sensitive approaches are crucial to the understanding of dating IPV.     

The Trajectory of Post-communist Welfare State Development: The Cases of Bulgaria and Romania

Governments of countries undergoing a post‐communist transition face the dilemma of balancing conflicting demands for greater economic efficiency (to achieve a successful transition to a market system) with demands for enhanced social protection (to legitimize regime change through a visible improvement in living standards which includes vulnerable groups). This paper analyses the transition in Bulgaria and Romania. Unlike other European countries, these countries did not embark on retrenchment policies until the mid‐ to late 1990s, so convergence with policies of spending constraint elsewhere in Europe was belated and partial. The social problems created by strict economic policies, exacerbated by a determination to reorganize the post‐communist welfare states along the lines promoted by international organizations, are now being recognized. Post‐communist governments in South‐eastern Europe have belatedly started to address the social aspects of transition to democracy and the market. This probably reflects the process of regime change in Bulgaria and Romania, which has been characterized as a “two‐step transition to democracy”, with liberal governments only succeeding transformed communist elites in power after a protracted transition.     

Childhood victimization and subsequent adult revictimization assessed in a nationally representative sample of women and men

The purpose of this study was to identify whether experiences of childhood physical and/or sexual victimization would increase women's and men's risk for victimization in adulthood by different perpetrators (any perpetrator regardless of the relationship to the victim; intimate partner perpetrator; non-intimate perpetrator) using a nationally representative sample. Results of hierarchical logistic regression analyses indicated that childhood victimization increased the risk for adulthood victimization by any perpetrator for men and women, and by an intimate partner for women but not men. Female and male victims of physical and/or sexual child abuse are at higher risk for adult victimization by non-intimate perpetrators. These results suggest the appropriateness of interventions among adults or young adults who have been victims of child abuse, to prevent any future victimization in adulthood. To guide the development of such prevention programs, research is needed to identify factors that affect the probability of adulthood victimization among child abuse victims.     

Participatory ergonomics: determining injury control "buy-in" of US Army cadre

Overuse injuries account for the majority of lost duty time profiles for soldiers attending Advanced Individual Training (AIT) to become a Combat Medic at Ft. Sam Houston (63% for men and 74% for women). An intervention program was initiated with two AIT Battalions (BN) in an effort to reduce overuse injuries. The purpose of this paper is to describe methods of tracking the participation of supervisors during the intervention program. Methods used to monitor participation included recording the number of coordinating meetings, keeping minutes of advisory committee meetings, and conducting perception surveys. Over an 18-month period, the number of coordinating meetings decreased. Surveys identified the opinions, values, and self-identified roles of supervisors (drill sergeants and cadre) in regard to injury prevention with their assigned student-soldiers before and after an intervention program. At the initiation of the injury control program, 103 individuals completed a 27 question, anonymous survey to assist planners with developing a strategy that would encourage participation of cadre and drill sergeants in preventing injuries. One year later, 191 individuals from the same battalion completed the same survey. Results revealed a slight, statistically insignificant, decrease in supervisors' perception of the presence of overuse injuries in their BN (31.4% vs. 27.4%, p>0.05), and the level of acceptable injuries moved from the 16-30% range to the 1-10% range (chi2=4.65, p<0.05). Post-intervention, more supervisors believed their physical training programs could impact overuse injuries (pre 20.4% vs. post 31.6%, Chi2=6.7, p<0.01). The results reveal several methods to track the involvement of participants, to develop intervention strategies, and to monitor cultural shifts necessary to the injury control process.     

What makes children defy their peers? Chinese and Spanish preschoolers' decisions to trust (or not) peer consensus

The more people agree on the same piece of information, the more likely are individuals to endorse the testimonial information. Children are sensitive to consensus but their trust in what a majority says also depends on the decision context, their previous knowledge, and, interestingly, the culture in which they develop. Here we study Chinese (N = 60) and Spanish (N = 48) preschoolers' sensitivity to the opinion of a group of peers in consensus regarding (a) peer interaction events and (b) use of artifacts. For each context, we varied the degree of ambiguity of the situations: unfamiliar, ambiguous, and familiar, where the majority offered a transgressive opinion in conflict with “common sense.” Children were more likely to trust their peers in the unfamiliar and ambiguous situations. In the familiar situations, children showed greater acceptance of transgressive claims regarding artifacts than peer interaction events. The two cultural groups, however, significantly differed in the degree of endorsement. Although Chinese children gave little credibility to their peers even when facing novel information, Spaniards deferred to them, even at the expense of their own criteria. Together with previous findings, these results indicate culture‐specific patterns related to children's attitudes toward peers versus adults as sources of knowledge.